There have been made many proposals for power management systems, and for power outlet units used for distribution of electric power. Power outlet units are specifically known as wall sockets and power strips. For example, according to one proposal for power outlets, a control signal that reflects operation on an operation panel is transmitted to each power outlet to control a power distribution controller provided in the power outlet, thereby to turn on and off the supply of electric power to a load. According to this proposal, each power outlet is provided with an address setter which assigns it a unique address so that, when an address included in a received transmission signal matches the one assigned to the power outlet by the address setter, the power distribution controller turns on and off a contact based on the control signal (Patent Document 1). Another proposal is directed to the reading of identifying information stored in IC tags in power plugs of electric appliances in the field of automatic control of electric appliances, a hot-water supply installation, etc. in a household through the monitoring of their energy consumption and operation status (Patent Document 2).